Christopher Tolkien, in Volume 5 of "The History of Middle-earth" (The Lost Road and Other Writings) showed that while JRRT's time travel story "The Lost Road" was never finished, the ideas he came up with for the story became the basis of the legend of Numenoreans.
Cool! :) I just got that for Christmas but haven't read it yet--will keep an eye out for that part.
BTW, what the article mentions about JRR coming up with LotR while Lewis came up with the Perelandra series is what I was misremembering when I said that was how Lewis came up with the Narnia series--it was actually Perelandra I was thinking of. I had read that whereas Perelandra involved space travel, LotR involved a distant time; so actually in that sense JRR's time travel idea was incorporated into LotR.